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| dc.contributor.author | Yabebal, Chekole Mihret | |
| dc.date.accessioned | 2022-12-31T08:00:24Z | |
| dc.date.available | 2022-12-31T08:00:24Z | |
| dc.date.issued | 2022-09 | |
| dc.identifier.uri | http://ir.bdu.edu.et/handle/123456789/14815 | |
| dc.description.abstract | Ethiopia started growing rice in the early 1970s, without giving much attention for post-harvest processing procedures, such as grain drying activities. The majority of rice crops are harvested when their moisture content is between 20% and 25%, that cause grain spoiling and degradation, mycotoxin contamination that results in losses, and poorer germination rates. Farmers in Ethiopia frequently used the open sun drying to bring the rice moisture content down to a level suitable for storage. But this approach linked to issues like subpar grains, discolorations, and cracking brought on by direct UV exposure, rain, dust, premature drying, and contamination. Due to the large initial investment and ongoing operating costs of the dryer, commercial mechanical dryers that can address the aforementioned issues are not within the means of small-scale farmers. Additionally, the majority of the country's rural areas are not serviced by the nation's electrical infrastructure. Therefore, mechanical dryers that are effective and save energy are preferred to solar and open-air drying. In this study an energy-efficient mixed-flow rice dryer that used rice husk as an energy source to produce the drying hot air was designed, fabricated, and its performance evaluated. The designed dryer had a 0.4×0.4×0.64m size and the furnace had a 0.3×1×0.3m size with a capacity of 30kg. The result of the experiment showed that the average drying air velocity used was 0.6m/s at the dryer air outlet section and 2.1m/s at the inlet of the heat exchanger with a volume flow rate of 0.054m 3 /s. The average temperature recorded during the experiment were 338.3℃ at the combustion chamber outlet, 113.4℃ at the chimney outlet, 63.3℃ at the heat exchanger outlet, 49.5℃ at the dryer inlet, 36.3℃ at the dryer outlet, and 26.4℃ for ambient air conditions. The dryer was capable of reducing the moisture content of the rice from 20.3% (wb) to 11.8% (wb) in 2.43hours. The maximum energy consumed during the experiment was 48.01MJ with 52.4% combustion chamber efficiency, 14.9% heat exchanger efficiency, 7.81% overall efficiency of the furnace, and 54.29% efficiency of the dryer. The drying kinetics of the rice was predicted using an empirical model, the prediction error was 1.15% (wb) in moisture content with the experimental results. The parametric study was also used to study the effect of temperature by using empirical model and the experimental results prediction error was 2.9℃ in temperature. The developed affordable rice dryer could have a significant contribution in reducing the postharvest loss of rice, and will increase the food security and income of the farmers. Keywords: Rice, Rice husk, Furnace, Mixed-flow dryer | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | MECHANICAL AND INDUSTRIAL ENGINEERING | en_US |
| dc.title | DEVELOPMENT AND PERFORMANCE EVALUATION OF SMALL-SCALE RICE HUSK-FUELED MIXED-FLOW RICE DRYER | en_US |
| dc.type | Thesis | en_US |
